*1:See also https://sumita-m.hatenadiary.com/entry/20140730/1406685196 https://sumita-m.hatenadiary.com/entry/20160228/1456655841 https://sumita-m.hatenadiary.com/entry/20181005/1538730662 https://sumita-m.hatenadiary.com/entry/2020/06/01/145035 https://sumita-m.hatenadiary.com/entry/2020/08/09/092055 https://sumita-m.hatenadiary.com/entry/2020/09/08/080509